The present invention is generally directed to the application of coatings onto print media, and is more specifically directed to a method for making a coating blanket for applying a coating solution onto the print media.
In printing items such as brochures, product packages, and the like, it is often desirable to enhance the durability or scratch resistance of the finished product, or to achieve a certain visual or tactile effect, such as a matte or glossy finish. In general, this is accomplished by selectively applying different coatings onto the print media. Usually, the coating is applied by passing the printed media, such as cardboard, under a roller or other surface having what is referred to by those skilled in the art as a xe2x80x9ccoating blanketxe2x80x9d attached thereon. The coating blanket is covered with a coating solution and engages the print media as it passes under the blanket. The coating solution is typically referred to by those skilled in the pertinent art to which the invention pertains, as xe2x80x9cvarnish.xe2x80x9d
To apply varnish only to certain portions of the print media, areal portions of the coating blank corresponding to non-coated areas on the print media are cut from the coating blanket. Normally, the coating blanket material is cut by hand introducing the likelihood of human error to the cutting process. In addition manually cutting the coating blanket results in long production times that cause corresponding increases in the cost associated with producing the final product.
In the past efforts to automate the coating blanket production process have been attempted. For example, flat bed type cutting machines wherein the coating blanket material is positioned on a flat surface and remains stationary while a numerically controlled knife traverses and cuts the material have been utilized. However, these machines are usually quite large and very expensive. Moreover, positioning the coating blanket material on the flat surface can be quite cumbersome since an operator must reach over the flat surface to orient the coating blanket.
Based on the foregoing, it is the general object of the present invention to provide a method for producing a coating blanket that overcomes the problems and drawbacks of prior art methods.
The present invention is directed to a method and material for making a coating blanket for use in printing presses wherein the coating blanket material includes at least a first layer of flexible material having an upper and a lower surface, and a second layer of semi-rigid material bonded to the lower surface of the first layer. A cutting machine is provided that includes a frame, a cutting surface mounted for rotation to the frame and adapted to engage the second layer of semi-rigid material, and thereby support the coating blanket material. Means for driving the coating blanket material in a first and second direction with the second direction being opposite to the first direction are also included, the means being responsive to commands issued from a controller having coating blanket cutting data stored therein. A support is mounted to the frame adjacent to and coaxial with the cutting surface and a cutter head is mounted to the support for movement back and forth therealong responsive to the cutting data stored in the controller. A knife for cutting the first layer of flexible material is also provided and is coupled to the cutter head for movement between a working position wherein the knife engages and extends through the first layer of flexible material, and a non-working position wherein the knife is positioned above the first layer of flexible material.
To facilitate a cutting operation, the coating blanket material is presented to the cutting apparatus with the second layer of semi-rigid material engaging the cutting surface and the upper surface of the first layer of flexible material facing the cutter head. During operation, the drive means causes the coating blanket material to move back and forth in the first and second directions responsive to the cutting data stored in the controller. Simultaneously, the cutter head moves relative to the upper surface of the coating blanket material, also in response to commands issued from the controller with the knife moving between the non-working and working positions, thereby generating lines of cut in the upper layer of flexible material. The operation continues until all of the cuts necessary to complete the desired coating blanket are made. Preferably, the knife is a drag-type knife pivotally mounted to the cutter head such that during a cutting operation, movement of the cutter head relative to the coating blanket material causes the knife to orient itself along a particular line of cut.
In one embodiment of the present invention, the second layer of semi-rigid material defines opposing lateral edge portions, each extending past a corresponding edge of the first layer of flexible material. A plurality of apertures are defined by each of the lateral edge portions with each aperture in one of the lateral edge portions being approximately aligned with a corresponding aperture in the other of the lateral edge portions. In this embodiment, the apertures are adapted to engage drive pins, which extend radially from a pair of sprockets, one of which is mounted to the frame adjacent to each end of the cutting surface.
Preferably, the apertures defined by the lateral edge portions as well as the drive pins extending from each sprocket are arranged in a pattern, thereby allowing the coating blanket material to be mounted onto the cutting apparatus in only one way. This prevents the possibility of mounting the coating blanket material to the cutting apparatus in a misaligned manner. In addition, the aperture pattern as well as the drive pin pattern on the sprockets can be employed to enable the controller to determine the position of the coating blanket material relative to the knife. For example, where a single differently sized drive pin or a series of differently sized drive pins are employed in the above-described sprockets, an encoder or other type of sensor can detect the position of the differently sized pin, thereby allowing the controller to determine the orientation and position of the coating blanket relative to the knife and the cutting data stored in the controller.
Due to the weight and rigidity of typical coating blanket materials, as the material is advanced through the cutting apparatus, significant overhang of coating blanket material relative to the cutting surface can develop. This overhung material results in large torque requirements to move the material back and forth through the cutting apparatus. To address this situation, another embodiment of the present invention is directed to the formation of a loop of coating blanket material mounted on the cutting apparatus. To form the loop, a sheet of coating blanket material is mounted on the cutting apparatus with a portion of the semi-rigid second layer being supported by the cutting surface. The coating blanket material is then wrapped around the cutting surface and the ends of the material are joined together such that the loop of coating blanket material encompasses the cutting surface. This prevents the coating blanket material from overhanging the cutting surface during a cutting operation, thereby requiring less torque to be generated by the drive means to move the coating blanket material back and forth relative to the cutter head. In fact, the drive means in this embodiment must only overcome the coating blanket material""s own inertia.
In each of the above-described embodiments, it may be desirable to cut sharp corners into the first layer of coating blanket material. To accomplish this, it is preferable that the knife of the present invention be a drag knife pivotally mounted to the cutter head such that the motion of the cutter head and coating blanket material relative to one another causes the knife to pivot and orient itself along the desired line of cut. To produce sharp corners, the present invention employs a method whereby the motion of the cutter head and the coating blanket material is halted, and the knife is moved from a position wherein it was cutting through the thickness of the first layer of flexible material to a point where a tip defined by the knife just contacts the upper surface of the first layer of flexible material. Next, the cutter head and the coating blanket material are moved relative to one another an amount sufficient to cause the drag knife to pivot and align itself with the knife""s cutting edge facing the desired direction necessary to form the angle defined by the corner. The drag knife is then plunged through the first layer of flexible material but not to a point where it would cut or score the second layer of semi-rigid material, and the cutting operation is continued.
An advantage of the present invention lies in the fact that the above-described method of creating a coating blanket does not rely on a manual cutting operation and thereby eliminates any potential for human error.
In addition, coating blankets can be created wherein the cut areas are formed with greater precision than would be possible in a manual operation.
Another advantage of the present invention is the incorporation of a drag knife as opposed to numerically controlled knives used in flat-bed type machines that require complex mechanisms to manipulate the knife, whereas a drag knife simply pivots relative to the direction of cut.